1. Field of the Invention
The invention relates generally to luggage, particularly to wheeled luggage. The invention allows luggage to be wheeled along a supporting surface while "upright," e.g., with the major axis of the luggage mostly vertical relative to the supporting surface, but also while reducing fatigue on the user's arms.
2. Background Art
Wheeled luggage cases have developed rapidly over recent decades. As early as the late nineteenth century, patent literature showed large wooden trunks with small metal wheels built into wood strips or skids. Conventional suitcases having horizontal major axes and either two or four wheels have been the standard of the industry for years. These cases, known as "pullman" cases, have the wheels attached to the bottom wall of the case. They are towed on these wheels by a strap or handle attached on an end wall near an upper corner of the case.
A conventional wheeled pullman has two fixed-axis wheels on the bottom. These are spaced from one another along the relatively narrow width dimension of the case to support the back end of the case. A pair of caster type wheels support the front end of the case. The user pulls the case around on these four wheels as if it were a rather narrow, tall wagon.
Another type of pullman, popularized by Samsonite Corporation, is known by the trademark "Cartwheels". This case has two fixed axis wheels mounted at a lower, rear edge of the bottom face of the case, and a pair of glides (small plastic or rubber legs), attached on the bottom near the front edge thereof. An elongated handle is mounted on a pivot axle on the upper portion of the front wall of the case. This handle is normally held flush against this wall when not in use. The axle mount includes an abutment against which the pivot end of the handle bears when the handle pivots to its outward most position that holds the handle outward from the case when it is pivoted from the stored position. In this position, the user can hoist the front of the case up, thus lifting the glides off the floor so that the case can be rolled on the back wheels.
Another style of wheeled, upright luggage case has a pair of fixed axis wheels spaced along a long edge of the lower face. These wheels are oriented so that the case is rolled broadside. The upper face of the case has a handle with which the user balances the case on these two wheels. One such case, popularized under the trademark "Piggyback" by Samsonite Corporation, incorporates luggage cart functions into this type of two wheeled case. Here, the wheeling handle is on an arm that slides upward out of the case to a convenient position. The user tips the case onto the wheels while simultaneously suspending an auxiliary case from the strapping device on a handle.
U.S. Pat. No. 1,757,490 to Tibbetts shows a wheeled hand truck that may be used to transport suitcases, but does not suggest tilting the truck's frame to improve stability and comfort while leaving four wheels in contact with the ground.
U.S. Pat. No. 2,596,578 to McIntyre, et al., discloses a suitcase with one pair of wheels to assist the user in carrying it along in an upright position. The suitcase cannot stand independently upright; the user must support and balance the case.
U.S. Pat. No. 3,861,703 to Gould discloses a way to mount four wheels on the bottom of an upright suitcase in order to roll it across a supporting surface. The case is not tipped during transport.
U.S. Pat. No. 4,679,670 to Wickman shows an upright wheeled suitcase, but the major axis of the case is perpendicular to the ground, which may reduce dynamic stability.
U.S. Pat. No. 5,044,476 to Seynhaeve discloses a suitcase that may be wheeled along in an upright position, but no particular angle of tilt is indicated as being desirable.
A need remains for an upright wheeled case that is stable when rolled and yet does not demand constant manual support by the user, with the resultant stress on the user's arm.